Dnia 09.05.2012 o 22:21 Ivan Lisenkov <i...@ivlis.com> Ivan Lisenkov <i...@ivlis.com> napisał(a):
> Hello everybody, > > I have reimplemented Patryk schematics with some minor changes. Photo > on breadboard is here: http://i.imgur.com/gUcFq.jpg . I can say that > it works :) I have lost about two days to figure out why the MC > doesn't get recognized by my laptop. The problem was in Zener diodes, > my were too powerful, one should use 0.5W and I had 1W. So I dropped > voltage from USB to 3.6V (two transistors on breadboard) and powered > MC and DS2482-800 by 3.6V. And I changed i2c pullup resistors to 2.2k, > as it suggested by DS2482-800 datasheet. I don't know if safely but in my case it all works also without diodes all on 5V. I tested without those diodes on my two laptops and nothing was damaged :) It's also mentioned on i2c-tiny-usb page that You can omit the diodes and according to USB specs nothing should happen. > > And some random thoughts, also: > > 1) I was told on some forum (it is in Russian, so links are useless > here), that DS2482-800 doesn't proceed 1-wire lines in parallel. If > so, I guess multiple (we can have up to 4) DS2482-100 will be much > better I have found a comparison of 1-wire masters. The short version is that the most powerful one is DS2480B the i2c ones are weaker. But on the other hand with -800 you get a switch so it's better with star topology. http://www.maxim-ic.com/app-notes/index.mvp/id/4206 Yes, the DS2482-800 just switches between buses but while the bus is inactive it has +5V power so maybe sensors can do the conversion. DS2482-100 does not have strong pull "inside" you have to add external transistor for that. I have my test board done. I just need to print it on a laser printer. It has place for all 3 i2c masters and you can disconnect each one with a jumper. Atmega8 has also a header to future experiments. It's one side board with few wires instead of bottom side. board http://ubuntuone.com/3XX2xi4AllOoJP2nC5rAIe schematics http://ubuntuone.com/4rrnNhILnhTiT7jCWYz4fU > > 2) If one can combine existing 1-wire master code for AVR (STM?) MCs > with existing usb code, we can obtain a "dream device", a native usb > 1-wire master in one cheap IC! I saw some guy mad a 1-wire master and posted on Polish forum elektroda.pl http://www.elektroda.pl/rtvforum/topic1524421.html It said to run on Linux with digitemp. -- p4trykx ------------------------------------------------------------------------------ Live Security Virtual Conference Exclusive live event will cover all the ways today's security and threat landscape has changed and how IT managers can respond. Discussions will include endpoint security, mobile security and the latest in malware threats. http://www.accelacomm.com/jaw/sfrnl04242012/114/50122263/ _______________________________________________ Owfs-developers mailing list Owfs-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/owfs-developers
